Spatial building models typically reproduce the physical characteristics of a building (such as the internal layout of rooms) in a scaled form. Most contemporary graphic building models are produced using computer modelling software.
Models of existing buildings are often produced when renovation work is planned (such as an interior remodelling). The models may be produced in two dimensions (such as a floor plan) or three dimensions depending on the type of work that is scheduled and modelling capabilities available.
Measurements for a graphic building model are commonly captured by a tradesmen or an estimator in advance of planned renovations. A tape measure or an optical distance meter may be used to obtain individual measurements of a room. These measurements are then typically recorded in a scrap book or digital file.
The measurements captured for a building are subsequently used by a draftsman to construct a computer model of the measured space. The draftsman creates the building model from the captured measurements and any notes taken by the surveyor.
The overall modelling process can be time consuming. Both the measurement and modelling aspects are typically performed by skilled workers with some previous experience. The tools used to capture the building measurements and the attentiveness of the individuals involved in both measuring and modelling the building can influence the accuracy of the final building model.